The UCLA/RAND Center for Adolescent Health Promotion's mission is to conduct prevention research that (1) addresses the needs of children, adolescents, young adults, and their families;(2) builds empowering relationships with community partners in Los Angeles and beyond;and (3) directly benefits communities and/or transforms local, state, and national policies. For ten years, our partner community has been LA's large, diverse South Bay region. Our core research project, Parents and Students for Nutrition and eXercise (P-SNaX), is a community-based participatory research (CBPR) project to develop and test a parent-focused intervention to improve childhood nutrition and exercise in homes and neighborhoods. P-SNaX builds on one of our existing successful CBPR projects (SNaX), a child-focused intervention to improve student nutrition and exercise in middle schools. Together, SNaX and P-SNaX may offer a sustainable comprehensive approach to childhood obesity prevention that, although recommended, has been elusive in practice. In Year 1, we will conduct surveys assessing parent needs with respect to their child's nutrition and exercise. We will then work closely with communities, parents, students, and schools to develop P-SNaX to increase parent self-efficacy and to stimulate change in homes and neighborhoods. In Years 2-5, we will test the intervention in four South Bay schools (SNaX + P-SNaX vs. SNaX-only), disseminate preliminary and final results, and prepare for a large-scale cluster-randomized trial. Our specific aims are: (1) To assess parents'needs, self- efficacy, and behaviors with respect to childhood obesity prevention in their homes, schools, and neighborhoods;(2) To develop a school-based, parent-focused CBPR intervention (P-SNaX), administered in conjunction with SNaX, to increase parent self-efficacy and improve child and parent behaviors with respect to childhood obesity prevention;(3) To conduct a four-school controlled trial (P-SNaX + SNaX vs. SNaX only) to examine the incremental effects of P-SNaX on healthy eating and physical activity among students;and (4) To disseminate results of the combined parent and student-focused intervention to community stakeholders, and to develop plans for broad program dissemination and additional research. RELEVANCE (See instructions): Childhood obesity is a national public health concern. Comprehensive approaches to childhood obesity prevention involving children, parents, schools, and communities are widely recommended, but the ability to deliver and sustain such programs has been lacking. Participatory research among researchers, families, schools, and communities may be able to find new, effective solutions.